Antimicrobial and antioxidant effects of edible nanoemulsion coating based on chitosan and Schizonepeta tenuifolia essential oil in fresh pork

The objectives of this study were to develop a nanoemulsion-based edible coating containing chitosan (CH) and Schizonepeta tenuifolia essential oil (STEO) and to investigate its coating effect on quality and shelf life of fresh pork stored at 4 ± 1°C for 16 days. Nanoemulsions with the average droplet sizes of 55.0–92.3 nm were prepared by subjecting coarse emulsions containing CH and STEO at 0.5%, 1%, and 2% (v/v) to ultrasonic emulsification. Zeta potential and polydispersity index of the prepared CH-STEO nanoemulsion were 45.5–57.3 mV and 0.17–0.28, respectively. The incorporation of 2% STEO into CH was applied as the coating formulation for pork slices. The coating treatments significantly prolonged the shelf-life of fresh pork by inhibiting microbial growth and retarding lipid oxidation. In particular, the CH-STEO nanoemulsion coating showed the best performance on meat preservation, which could be attributed to its smaller particle size with enhanced preservative function and stability. The study suggested that the active nanoemulsion loaded biopolymer edible coating has great potential for fresh meat preservation. Novelty impact statement This work investigates the effect of nanoemulsion-based edible coating containing chitosan (CH) and Schizonepeta tenuifolia essential oil (STEO) on quality and shelf life of fresh pork stored at 4 ± 1°C for 16 days. The results indicated that nanoemulsification was an effective approach to improve the physicochemical and bioactive properties of CH-STEO coating solution. Application of CH-STEO nanoemulsion (2% EO) coating in fresh pork significantly inhibited microbial growth and lipid oxidation during refrigerated storage.